Locomotive draft sheet



O. LARSQN LOCOMOTIVE DRAFT SHEET Filed Jan. 23, 19:59

Patented Dee. 31, 1940 UNITED STATES PATENT OFFICE 3 Claims.

In ordinary locomotive practice the exhaust produces a powerful draft, particularly when the locomotive is on a steep grade, which lifts and agitates the fuel bed with the result that many smaller cinders are drawn up over the brick arch and into the flues, especially the lower ones, so that on a long hard run many of these ues fill up to an extent that renders them nearly useless thereby greatly reducing the eiciency of the boiler. After every run these ues must be carefully cleaned at considerable expense and with consequent loss of the use of the locomotive.

Moreover, smaller cinders or burning pieces of coal pass through the flues and out the stack and are strewn along the right of way with the attendant danger of starting fires in hot dry weather.

An object of this invention is to provide an improved form of locomotive draft sheet which will insure a more steady and uniform draft throughout the boiler hues and fire box resulting in fewer cinders, or none at all, being drawn over the brick arch into the ues.

Another object is the provision of means for bringing about a more uniform distribution of draft over the grate area and throughout the various flues of the boiler, with resultant equalization of velocity in the travel of cinders to and through the liues, thereby reducing greatly the damage from cinder cutting.

These and other objects as will hereinafter appear are accomplished by this inventionl which is fully described in the following specication and shown in the accompanying drawing in which Figure 1 is a longitudinal vertical section through a locomotive boiler embodying the invention; and

Fig. 2 is an enlarged partial elevation on the line 2 2 of Fig. 1.

The embodiment illustrated comprises a locomotive boiler having a fire box I0 with grates II over which extends a brick arch I2. The boiler is enclosed by boiler plates I3 with boiler head plates I4 and, I5 into which are secured the ends of the boiler ues in any well known manner. These boiler flues consist of the small ues I6 near the bottom of the boiler and the large ues Il near the top which usually enclose the superheater tubes which are not shown as they form no part of the present invention.

In front of the boiler head plate is a smoke box I 8 which overlies the locomotive cylinders I9 and which terminates in a smoke stack 20. A

table plate 2| lies horizontally across the smoke box near its center and connects with a baille plate 22 which extends up and over the forward ends of the flues. The plates ZI and 22 are connected to the fire box shell 23 so as to divide the smoke box into upper and lower compartments `5 24 and 25. An exhaust nozzle 26 passes through the tableI plate 2|, the exhaust from the cylinder serving to supply the draft for the flues.

A screen 2l usually extends from. the table plate 2I across the upper portion of the smoke 10 box to prevent the passage of cinders of larger than a predetermined size. The forward end of the smoke box is closed by a front head plate 28. The table plate 2l may be provided with a downturned flange 29, the space therebelow being free 15 for the passage of flue gases in the usual way.

Myinvention consists in placing a draft sheet 30 so as to substantially cover the opening beneath the table plate 2|. This sheet is shown in Fig. 2 and preferably has the form of a segment 20 of a circle, the straight side 3| of which lies horizontally in position to overlie the flange 29, if desired, and has a series of holes 32 through which pass bolts, not shown, for securing it fixedly in place. The arcuate portion 33 is formed to 25 t the curvature of the smoke box shell 23 and is secured thereto by a series of brackets 34, Fig. 1, by means of bolts, not shown, passing through holes 35 in the draft sheet. This plate is perforated with a series of small holes 36 at the top 30 and increasing in size to large holes 3l at the bottom. I have also preferably cut notches 38 from the bottom of this sheet so as to direct the flue gases toward the bottom to agitate any cinders which might be carried through the flues 35 and to cause them to be thrown up against the screen 2l where they will be broken up into pieces fine enough to pass through the screen and out the stack.

The arrangement of small holes toward the 40 top of this draft sheet with holes of increasing size toward its bottom has the effect in practice of maintaining a very uniform distribution of gases through the various flues. Thus the relatively larger aggregate free area for the passage 45 of gases through the bottom of the sheet 30 increases the draft through the lower and smaller ues I6 thereby insuring that they will be kept nearly free of cinders. Instead of frequent cleaning of the nues, particularly the lower ones, as 50 heretofore has been necessary, it is found that by the use of this draft sheet, there is little tendency of the fuel bed to be lifted off the grates, and that substantially no cinders, even the smaller ones, are drawn over the brick arch. As a con- 55 some of it thrown over the brick arch and into Where the flues, particularly the lower ones. this draft sheet is used, it is found that the fuel bed is not greatly disturbed even under these excessive conditions and that ,even then few cinders are drawn over the brick arch and that these when present are of small size anddo notI tend to clog the flues.

While I have shown and described but a single embodiment' of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

l. The combination with a locomotive boiler having flues positioned in various horizontal planes, the diameters of the flues diminishing toward the bottom of the boiler, and, forwardly of the flues, a smoke box with an opening therethrough, of a draft sheet adapted for tting within the opening of the smoke box at a point substantially opposite the forward ends of the lower boiler flues of lesser diameter and in spaced relation thereto, the draft sheet being formed therethrough with a plurality of openings Whose aggregate area increases toward the bottom of the sheet, the bottom edge of the draft sheet 'being cut away to permit the passage of flue gases adjacent the bottom of the smoke box.

2. The combination with a locomotive boiler having ues positioned in various horizontal planes, the diameters of the nues diminishing toward the bottom of the boiler, and, forwardly of the nues, a smoke box with an opening therethrough, of a draft sheet adapted for tting Within the opening of the smoke box at a point substantially opposite the forward ends of the lower boiler flues of lesser diameter and in spaced relation thereto, the draft sheet being formed therethrough with a plurality of openings varying in size with the largest near the bottom of the sheet, the bottom edge of the draft sheet ,being cut away to permit the passage of flue Vgases adjacent the bottom of the smoke box.

3. In combination, a locomotive boiler having at one end a fire box wherein is a fuel grate `with an arch thereover, the boiler having fiues positioned in various horizontal planes, the diametersA of the flues diminishing progressively toward the bottom of the boiler, and, forwardly of the flues, a smoke box with an opening therethrough, power means for inducing a draft through the boiler and out through the smoke box, a draft sheet adapted for fitting within the opening of the smoke box at a point substantially opposite the forward ends of the lower boiler flues of lesser diameter, in spaced relation thereto, and in the line of draft proceeding out of the smoke box, the draft sheet being formed therethrough with a plurality of openings whose aggregate area increases progressively toward the bottom of the sheet in substantially inverse proportion to the decrease in the diameter of the flues of the boiler whereby to cooperate with the ues of lesser diameter in equalizing the draft distribution through the boiler with a consequent diminution of pull on the cinders tending to lift them off the fuel bed resting on the grate and thence over the arch for passage through the boiler, and means located opposite the upper boiler fiues for preventing direct draft from said upper ues through the smoke box.

OTTO LARSON. 

